The present invention relates to a protective structure for the floor of a concrete enclosure having to receive a fluid which can be raised to a high temperature, such as liquid sodium or a hydrocarbon.
An enclosure of this type can be more particularly used for carrying out tests in a large volume (several dozen tons) of sodium, petrol or a comparable fluid. Such an enclosure may merely constitue a liquid sodium retention enclosure, e.g. on the site of a fast neutron nuclear power station. It is desirable to be able to place a thermal protection for the concrete of the enclosure in the latter.
Moreover, the protective structure must be tight, so as to ensure that the fluid contained therein does not penetrate the concrete. More particularly, when the concrete contains sodium at a temperature of 200.degree. C., the direct interaction between the sodium and the concrete would initially lead to a reaction between the sodium and the water contained in the concrete leading to the production of hydrogen and soda and would then lead to an infiltration of sodium into the concrete at a rate of 50 to 70 mm/hour. The hydrogen could then react with the oxygen in the air and cause a detonation, whose shock wave would entrain atomized sodium.
It is also desirable to have a protective structure, whose floor is as flat as possible and this flatness must be maintained no matter what the temperature of the fluid, i.e. independently of the differential expansion of the structure and the concrete enclosure. These characteriztics make it possible to prevent the formation of cracks in the protective structure and prevent the appearance of hotpoints resulting from a very localized punctiform contact. In certain applications, it may also be necessary to have a structure, whose floor is particularly flat, in order to permit the carrying out of manipulations on an air cushion before filling the enclosure. Finally, it is desirable to have a protective structure, which has a relatively low cost price and which can be easily repaired. To this end it must be possible to produce the protective structure in situ, within the actual enclosure which is to contain the fluid.